1. Field of the Invention
The present invention relates to a meandering detection device and a meandering detection method for detecting meandering of a subject. The present invention also relates to a meandering correction device including the meandering detection device for detecting meandering of a subject. The present invention further relates to an image forming apparatus including the meandering detection device for detecting meandering of a revolving endless belt.
2. Description of Related Arts
An image forming apparatus including a conventional meandering detection device is disclosed in JP-A-H8-106237. This meandering detection device detects meandering of an endless belt that conveys a recording sheet of an image forming apparatus that is formed of a color copier, to transfer an image. The meandering detection device has a lever-type, turnable pivoted contact, one open end of which abuts a side surface of the endless belt in revolving movement. The meandering detection device also has a light emitting element and a light receiving element arranged to face each other. At the other end of the contact, a shutter is provided which partitions the light emitting element and the light receiving element therebetween by turning.
Meandering of the endless belt causes the contact to turn, whereby the light emitting element is covered by the shutter. In accordance with the amount of meandering of the endless belt, the amount of light received by the light receiving element varies. Thus, the amount of meandering can be detected based on an output of the light receiving element. Accordingly, the travel of the endless belt can be so adjusted to correct the meandering, thereby preventing color shift of a plurality of colors.
However, the amount of light emitted by a light emitting device such as an LED varies depending on the ambient temperature. Thus, with the conventional meandering detection device described above, even when the endless belt is not meandering, an increase in the ambient temperature decreases the amount of light received by the light receiving element, thus resulting in erroneous detection that meandering is occurring. This poses a problem of color shift occurring in the image forming apparatus.